The invention relates generally to inflatable mattresses and cushions used for comfort and the prevention and treatment of pressures sores and, more particularly, an apparatus for attaching a valve to an inflatable cushion and attachable valves.
More particularly the disclosure relates to an improved apparatus for mounting a valve as well as the valves for use with an inflatable mattress or cushion having normally isolated zones to place the normally isolated zones in communication with each other or with the atmosphere in any desired arrangement of communication. The valve has improved attachment and sealing features.
Those individuals who are confined to wheelchairs run the risk of tissue breakdown and the development of pressure sores, which are extremely dangerous and difficult to treat and cure. Typically, much of the individual's weight concentrates in the region of the ischia, that is, at the bony prominence of the buttocks, and unless frequent movement occurs, the flow of blood to the skin tissue in these regions decreases to the point that the tissue breaks down. Cushions that are especially designed for wheelchairs exist for reducing the concentration of weight in the region of the ischia, and these cushions generally seek to distribute the user's weight more uniformly over a larger area of the buttocks.
Cellular cushions provide the most uniform distribution of weight and thus provide the greatest protection from the occurrence of pressure sores. These cushions have an array of closely spaced air cells that project upwardly from a common base. Within the base the air cells communicate with each other, and thus, all exist at the same internal pressure. Hence, each air cell exerts essentially the same restoring force against the buttocks, irrespective of the extent to which it is deflected. U.S. Pat. No. 4,541,136, which is incorporated herein by reference, shows a cellular cushion currently for use on wheelchairs.
In a sense the typical cellular cushion provides a highly displaceable surface that tends to float the user. While this reduces the incidence of pressure sores, it detracts from the stability one usually associates with a seating surface. Most of those confined to wheelchairs have little trouble adjusting to the decrease in stability, but for those who have skeletal deformities, particularly in the region of the pelvis and thighs, and for those who lack adequate strength in their muscles, lesser stability can be a source of anxiety. A variation of the cellular cushion addresses this problem with totally isolated zones and also with cells of varying height. By varying the volume of air between zones, for example, one can accommodate for skeletal deformities while still maintaining satisfactory protection against pressure sores. U.S. Pat. No. 4,698,864, which is incorporated herein by reference and owned by the assignee of the instant invention, shows zoned cellular cushion with cells of varying height.
Typically, a zoned cellular cushion has a separate filling stem and valve for each of its zones. The user simply opens the valve of each stem and introduces air into the zone for the stem, usually with a hand pump, and then releases the air from the zones until the desired posture is achieved. In a more sophisticated arrangement, a hose kit connects a single pump to a manifold, which in turn is connected to the several valves through separate hoses. Those hoses are fitted with separate hose clamps so that the air from the pump may be directed to the cells of the individual zones independently. Likewise, the air can be released from them independently, all by manipulating the clamps.
The hoses of the hose kit lie externally of the cushion and may become entangled in the components of a wheelchair. Furthermore, by reason of their remote locations, the hose clamps are difficult to manipulate. Examples of zoned inflatable cushions that demonstrate significant advantages from zoning are provided in U.S. Pat. No. 5,163,196 and U.S. Pat. No. 5,502,855, both of which are incorporated herein by reference.
In general, in a zoned cushion, the valve is open to allow communication between the zones and cushion is properly inflated or over inflated and the air flows to all the zones to reach a state of equilibrium. The cushion is placed on a proper support surface and the user is seated on the cushion and optimally positioned. Air is slowly let out of the cushion until the buttocks of the seated user sink deeper into the array of cells until the cells tend to envelope and assume the contour of the buttock. For example, enough air is released to bring the Ischia to within about ½ inch from the bottom of the cushion. All cells remain at essentially same internal pressure. When the user reaches optimal immersion, the user moves or is moved to a posture desired to be maintained for an extended period of time. This can cause a redistribution of air among the inflation zones until they reach a desired equilibrium for that particular user. The pressure in each zone is optimally achieved and the valve is closed to maintain the optimal pressure or restoring force in each zone.
The present invention is an improvement on valves required by zoned cellular cushions. Heretofore, the zoned cushions employed integral channels or conduits which lead from the several zones and which are connected through an integral common manifold and associated valve. One such valve comprises a flap that is folded over to seal off the ends of the channels or opened to allow communication between the zones through a manifold contained within the flap. Through use it has been determined that these flap-type valves and other prior art zoned cushion valves suffer from some drawbacks. First, in the flap-type valve, the flap has to be manually folded closed and secured with a snap or the like. Often these types of apparatus are difficult for a disabled individual to manipulate. The flap can be awkwardly positioned under the cushion.
Newer valves designed to prevent leakage are the subject matter of U.S. Pat. Nos. 6,687,936 and 6,564,419, both of which are incorporated herein by reference. Although these newer valves work well for their intended purposes and represent an improvement over previous designs, the inventors have developed novel valve designs that employ fewer parts, are more economical and simple to assemble and incorporate an improved apparatus for attachment of a valve to the cushion. Furthermore, the new valve designs are easier to operate by a person having limited hand function. The valves operate with less force than prior art valves.